65 Questions
Which keyword is used to pause execution of the executeAsyncTask function until promise settles?
await
If the promise is rejected, what happens?
An error is thrown
Which of the following is an example of an HTTP request method?
All of the above
What does the HTTP status code 404 indicate?
Page or resource not found
What does the term 'CORS' stand for?
Cross-Origin Resource Sharing
If the promise is fulfilled, where does the fulfilled value assign to?
data
Which method is used to extract the JSON data from the response object?
json()
Which HTTP method is used to update a specific resource with new data?
PUT
Which HTTP status code is returned when a webpage or resource does not exist?
404
What does the 'Content-Type' header indicate in an HTTP request?
The type of data in the request body
What are the two fundamental ways of handling asynchronous operations in JavaScript?
Callbacks and Promises
Which method is used to extract the JSON data from the response object?
json()
Which of the following is an example of an HTTP request method?
GET
According to the text, what does HTTP stand for?
Hypertext Transfer Protocol
What does HTTP define?
How messages should be formatted and transmitted
What property is used to specify the POST request in the Fetch API?
method
Which method is used to extract the JSON data from the response object in the Fetch API?
json()
Which of the following is an example of an HTTP request method?
DELETE
What are the two dialogues between web servers and browsers?
Request and Response
What is the response for successfully creating a new database entry?
201
What is the HTTP status code for successfully fetching data?
200
What is the HTTP status code for trying to fetch a webpage or resource that doesn't exist?
404
What is the HTTP response for successfully deleting an item where no content is returned?
204
What is the HTTP response for trying to access protected resources without proper authorization?
401
What is the HTTP response for an error in server-side scripting causing a request to fail?
500
What does the HTTP method 'POST' do?
Sends data to a server to create a new data entry
Which of the following is an example of using the 'PUT' method?
Updating user profile information
What does the 'DELETE' method do in HTTP?
Deletes a specified resource
What is the primary purpose of the 'headers' in an HTTP request?
To provide information about the request and the client making it
How is the 'headers' function in HTTP similar to the 'GET' method, but only requesting for headers?
It retrieves only the metadata about the requested resource without the actual content
Which of the following is an example of using the 'headers' function or similar functionality in HTTP?
Checking if a webpage exists before fetching its content
What is the primary purpose of the 'headers' in an HTTP request?
To provide additional information about the request or response
How is the 'headers' function in HTTP similar to the 'GET' method, but only requesting for headers?
It retrieves metadata about the requested resource without the actual content
What is the purpose of Cross-Origin Resource Sharing (CORS) in web development?
To allow resources on a web page to be requested from another domain
What does CORS prevent in web development?
Malicious scripts from accessing data from other websites
How does CORS impact web application development?
Enables making requests to APIs from the application
What is the purpose of try/catch statements in JavaScript?
To catch and handle errors or exceptions
Where is the code that may potentially throw an exception placed?
In the try block
What does the catch block contain in a try/catch statement?
The code that will be executed if an error is thrown in the try block
What is the primary purpose of asynchronous programming in JavaScript?
To ensure non-blocking code execution
Which type of actions in JavaScript commonly use asynchronous programming?
Network requests
What happens if time-consuming actions in JavaScript are performed without asynchronous programming?
The application freezes until the action is complete
What is a callback function in JavaScript?
A function passed as an argument to another function and executed after its parent function has finished execution
How is a callback function used in JavaScript?
Passed as an argument to another function and executed after its parent function has finished execution
What is the primary purpose of a callback function in JavaScript?
To handle asynchronous operations and execute code after a parent function has finished execution
What represents a value that may not be available yet but will be resolved at some point in the future, or it might get rejected?
Promise
In a Promise, what state indicates that the operation completed successfully?
Fulfilled
What is the primary improvement of Promises over callbacks for handling asynchronous operations?
Providing a more concise and clean syntax
What is the state of a Promise when its result hasn't yet been determined?
Pending
What state does a Promise enter if the operation fails?
Rejected
What does the Fetch API return?
A Promise that resolves to the Response object
Where is the Fetch API built into in JavaScript?
The global scope of JavaScript
What is the purpose of using async/await syntax with the Fetch API?
Easier handling of the Promise returned by the Fetch API
What type of request is being made in the provided code example?
GET
What will be logged to the console in the code example?
The JSON data fetched from the external resource
What does the Fetch API return?
Promise resolving to the Response object
What happens if an error occurs during the fetch operation?
The catch block is executed, logging the error to the console
What is the purpose of the catch block in a fetch operation?
To handle and log errors that occur during the fetch operation
What is the role of the browser when an error occurs during a fetch operation?
It logs the error to the console
How can you modify the code example to make a POST request instead of a GET request?
Change the URL in the fetch function to the desired endpoint
What is the correct way to specify a POST request in the Fetch API?
Add a method: "POST" property to the options passed to the fetch function
What should be done to send data with a POST request using the Fetch API?
Include a 'body' property in the options passed to the fetch function
What does the 'body' property do in the Fetch API POST request?
It provides the data to be sent with the request
What is the purpose of the 'headers' property in the Fetch API POST request?
It sets the content type of the request
What is the role of the 'catch' block in the provided code example?
To handle any errors that occur during the fetch operation
Study Notes
Async-await and Promises
-
awaitkeyword is used to pause execution of theexecuteAsyncTaskfunction until promise settles. - If the promise is rejected, an error is thrown.
- If the promise is fulfilled, the fulfilled value is assigned to the variable on the left side of the assignment.
HTTP Requests and Responses
-
GET,POST,PUT,DELETEare examples of HTTP request methods. - HTTP status code 404 indicates that the webpage or resource does not exist.
- CORS stands for Cross-Origin Resource Sharing.
-
Content-Typeheader indicates the type of data being sent in an HTTP request.
Fetch API
-
json()method is used to extract the JSON data from the response object. -
POSTrequest is used to create a new resource with new data. -
putmethod is used to update a specific resource with new data. -
deletemethod is used to delete a specific resource. -
headersproperty is used to specify headers in an HTTP request.
CORS and Errors
- CORS prevents web pages from making requests to a different origin (domain, protocol, or port) than the one the web page was loaded from.
- CORS prevents cross-site request forgery attacks.
- CORS impacts web application development by requiring additional configuration for cross-origin requests.
Try-Catch Statements
-
tryblock contains code that may potentially throw an exception. -
catchblock contains code that will be executed if an exception is thrown. - The primary purpose of
try-catchstatements is to handle exceptions and errors in JavaScript.
Asynchronous Programming
- Asynchronous programming is used to perform time-consuming actions without blocking the execution of other code.
- The primary purpose of asynchronous programming is to improve the responsiveness and performance of web applications.
Callbacks and Promises
- A callback function is a function that is passed as an argument to another function.
- A callback function is used to handle the result of an asynchronous operation.
- Promises represent a value that may not be available yet but will be resolved at some point in the future, or it might get rejected.
- The primary improvement of Promises over callbacks is that Promises provide a more readable and manageable way of handling asynchronous operations.
Test your knowledge on HTTP with this informative quiz. Learn about what HTTP stands for, what it transfers over the internet, and how it defines message formatting and transmission. Discover the role HTTP plays in making requests to APIs and receiving responses. Challenge yourself with questions on the dialogue between web servers and browsers.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
